This project will be concerned primarily with the analysis of the way that visual neurones encode motion and directionality. The approach will be comparative. Intracellular recordings will be made from cells in the medullas of flies and in retinal cells of vertebrates in an effort to follow the flow of information about movement from receptors to directionally-selective cells. Intracellular stainings will be used to help define the "wiring diagrams" of the cells. Experiments will attempt to provide a cross-fertilization of the stimulus approaches used to analyze directionality in vertebrate retinal cells on the one hand, and those developed for nonlinear analyses of turning behavior in insects, on the other hand. Secondarily, experiments with spectral sensitivities of dragonfly ocellar cells will concentrate on the origins of these cells' two discriminable chromatic mechanisms. Behavioral tests will continue on modifications of circadian activity rhythms of spiders by spectral lights so as to determine how these animals use the dual spectral sensitivities of their visual cells in color vision. BIBLIOGRAPHIC REFERENCES: A. Cerf-Beare and R.D. DeVoe, Automated analysis of circadian rhythm activity of small arthropods. Behavior Research Methods and Instrumentation, 7, 339-347, 1975. R.D. DeVoe and E.M. Ockleford, Intracellular responses from cells of the medulla of the fly, Calliphora erythrocephala. Biol. Cybernetics 23, 13-24, 1976.